Analysis of inhibitory mechanisms on Ca^<2+>-dependent K^+ channel influenced by exposure to a time-varying strong magnetic field.

分析时变强磁场暴露对Ca^2依赖性K^通道的抑制机制。

基本信息

批准号：
09680526
负责人：
IKEHARA Toshitaka
金额：
$ 2.18万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

We tested the effects of exposure to following two magnetic fields (MF) on cultured cells.(a) A time-varying MF changing between 0.07 and 1.7 T at an interval of 3 sec.(b) Extremely-low-frequency (ELF) ME (800 gauss, 50 Hz).(1) Effects of ME (a) on HeLa cells :K^+ uptake was activated and the intracellular Ca^<2+> concentration was increased by replacement of normal medium to high K^+ medium. A membrane-permeable Ca^<2+> chelating agent and Ca^<2+>-dependent K^+ channel inhibitors were found to reduce the K^+ uptake. Exposure to the MF partly inhibited the drug-sensitive K^+ uptake and completely suppressed the increase in intracellular Ca^<2+> in the high K^+ medium. But the inhibition of K^+ uptake by the MF was not restored by addition of Ca^<2+> ionophore. The suppression of K^+ fluxes could relate to a change in electric properties of cell surface and an inhibition of Ca^<2+> influx or Ca^<2+> release from cellular Ca^<2+> stores.(2) Analysis of ELF MF(b) effects on HeLa cells by FT-IR spectra :In analysis of the spectra of the 1500-1700 cm^<-1> region, absorbance of amide II mode (1540 cm-1)was decreased and a band about 1600 cm^<-1> was increased instantly by the MF.Increase in absorbance of the latter band reveals the increase on C=O symmetric vibration of free carboxyl. This results suggest changes in the protein structure of cell membrane and electric properties of cell surface.(3) Effects of ELF MF(a) on bovine adrenal chromaffin cells :We tested the effects of exposure to the time-varying MF(a) on transient increase in intracellular Ca^<2+> stimulated by bradykinin in chromaffin cells. Addition of bradykinin induced the increase in intracellular Ca^<2+> within few minutes.The exposure to the MF perfectly suppressed thc increase in cellular Ca^<2+> in Ca^<2+>-free medium. The inhibition occurred for 15 rain when the maximum magnetic flux density was more than 1.4 T.These results suggest that the exposure inhibits Ca^<2+> release from cellular vesicles.

我们测试了暴露于以下两个磁场（MF）对培养细胞的影响。（a）在3秒的时间间隔变化的MF在0.07至1.7 t之间变化。（b）极低的频率（ELF）ME（ELF）ME（800 Gauss，50 Hz，50 Hz，50 Hz）。替换正常培养基为高k^+培养基。发现膜可渗透的Ca^<2+>螯合剂和Ca^<2+> - 依赖性K^+通道抑制剂可减少K^+的吸收。接触MF部分抑制了对药物敏感的K^+摄取，并完全抑制了高K^+培养基中细胞内Ca^<2+>的增加。但是，没有通过添加Ca^<2+>离子载体来恢复MF对K^+摄取的抑制作用。 K^+通量的抑制可能与细胞表面电性能的变化以及Ca^<2+>涌入或Ca^<2+>抑制从细胞Ca^<2+储存中释放。（2）ELF MF（B）对HELA细胞对FT-IR光谱的影响的分析：在1500-1700 cm^<-1> 1500 cm^<-1>的分析中， cm-1）减小，并通过MF的吸收率立即增加了约1600 cm^<-1>的带，这表明c = o游离羧基的对称振动的增加。该结果表明细胞膜的蛋白质结构和细胞表面的电性能变化。（3）ELF MF（A）对牛肾上腺染色体细胞的影响：我们测试了暴露于时间变化的MF（a）对脑脂肪素细胞刺激的细胞内CA^<2+>瞬时CA^<2+>的影响。添加心动激肽在几分钟内诱导了细胞内Ca^<2+>的增加。接触MF在Ca^<2+>中完全抑制了细胞Ca^<2+>的THC增加。当最大磁通密度大于1.4 t时，发生了15个雨的抑制作用。这些结果表明，暴露抑制了Ca^<2+>从细胞囊泡中释放。